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Saskatoon synchrotron shines light on fertilizer made from human waste

Using the Canadian Light Source in Saskatoon, scientists say they have proven it is possible to create nitrogen-rich fertilizer from human waste.
Using the Canadian Light Source in Saskatoon, scientists say they have proven it is possible to create nitrogen-rich fertilizer from human waste. File Photo / Getty Images

The Saskatoon synchrotron had a hand in testing the feasibility of making fertilizer out of human waste.

Cornell University professor of soil and crop sciences, Johannes Lehmann, and his research team wanted to see if urine could benefit farmers in Kenya.

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“We were interested in figuring out how to bring nitrogen out of the liquid waste streams, bring it onto a solid material so it has a fertilizer quality and can be used in this idea of a circular economy,” he said in a press release.

While other high-tech adsorbers like carbon nanotubes have been engineered to capture and hold nitrogen gas, Lehmann’s team took a closer look at the toilet bowl.

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The scientists heated human feces to make pathogen-free charcoal called “biochar.” Next, they primed it with carbon dioxide which enabled the biochar to soak up nitrogen-rich ammonia gas given off by urine.

The high-resolution spherical grating monochromator beamline at the Canadian Light Source (CLS) enabled them to examine the chemical process and also provided an indication of just how well their material could make nitrogen available to plants.

“In order to understand what the interactions are between nitrogen, the ammonia gas and the carbon, there really is no other good way than using the NEXAFS [near-edge, X-ray absorption fine structure] spectroscopy that the CLS beamline offers,” Lehmann said in a statement.

“It was really our workhorse to understand what kind of chemical bonds are appearing between the nitrogen gas and our adsorber.”

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Officials said the discovery has the potential to increase agriculture yields in developing countries and reduce contamination of groundwater caused by nitrogen runoff.

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“I do think it is as important for a Saskatchewan wastewater treatment plant, or a dairy farm in upstate New York, as it is for a resident in Nairobi,” Lehmann said in a press release.

“It’s a basic principle that has utility anywhere.”

The research team is still looking into how their material compares to existing commercial fertilizers and if a cost-effective machine can be built to perform the process automatically.

Located at the University of Saskatchewan, CLS annually hosts over 1,000 scientists from around the world who use it to conduct health, agricultural, environmental and advanced materials research.

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